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- Water-Year Summary reports summarize a year of hydrologic data in a printer-friendly format.
- For water years 2014 onward, choose a water year and parameter and an on-demand Water-Year Summary report will be generated.
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USGS Water-Year Summary 2024
11098000 Arroyo Seco near Pasadena, CA
LOCATION - Lat 34°13'20", long 118°10'36" referenced to North American Datum of 1927, in NW 1/4 NE 1/4 sec.31, T.2 N., R.12 W., Los Angeles County, CA, Hydrologic Unit 18070105, on right bank, 0.7 mi east of Angeles Crest Highway, 1.5 mi upstream from Millard Canyon, and 5.5 mi northwest of Pasadena.
DRAINAGE AREA - 16 mi².
REVISIONS HISTORY - WSP 1315-B: 1914 (instantaneous maximum discharge), 1918 (instantaneous maximum discharge), 1920-21 (instantaneous maximum discharge). WSP 1928: Drainage area.
SURFACE-WATER RECORDS
PERIOD OF RECORD - December 1910 to January 1913 (fragmentary), April 1913 to November 1915, April 1916 to current year.
GAGE - Water-stage recorder. Broad-crested weir since November 1938. Datum of gage is 1,397.88 ft above NGVD of 1929. Prior to Oct. 1, 1916, nonrecording gage at different datum. Oct. 1, 1916, to Oct. 19, 1945, water-stage recorder at datum 4.00 ft lower.
REMARKS - No regulation or diversion upstream from station. See schematic diagram of San Gabriel River and Los Angeles River Basins available from the California Water Science Center.
EXTREMES FOR PERIOD OF RECORD - Maximum discharge, 8,620 ft³/s, Mar. 2, 1938, gage height, 9.42 ft, present datum, on basis of slope-area measurement of peak flow; no flow at times in some years.
